In wireless communications systems downlink and uplink transmissions may be organized into two duplex modes: frequency division duplex (FDD) mode and time division duplex (TDD) mode. The FDD mode uses a paired spectrum where a gap in frequency domain is used to separate uplink (UL) and downlink (DL) transmissions. In TDD systems, an unpaired spectrum may be used where both UL and DL are transmitted over the same carrier frequency. The UL and DL are separated in non-overlapped time slots in the time domain.
Third generation partnership project (3GPP) long term evolution (LTE) TDD homogeneous systems operate synchronously in order to avoid UL/DL inter-cell interference between base stations or nodes, such as enhanced Node Bs (eNode Bs) and/or mobile terminals, such as user equipment (UEs). A geographic region served by an eNode B is commonly referred to as a cell. Cells in a network typically use the same UL/DL configuration for synchronous operation of the LTE-TDD homogeneous systems. The UL/DL configuration includes frame configuration and UL/DL resource allocation within one radio frame. Additionally, the network can use the UL/DL configuration to align frame transmission boundaries in time. The synchronous operation can be effective to mitigate interference. However, the synchronous operation is not optimized for traffic adaptation and can significantly degrade packet throughput for small cells in a heterogeneous network (HetNet).
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.